1. Field of the Invention
The present invention relates to an optical device, a control method therefor, and a storage medium storing a control program therefor. Particularly, the present invention relates to a shake correction process technology of preventing image blur caused by camera shake etc. by using a plurality of shake correction lenses.
2. Description of the Related Art
Generally, in an image pickup apparatus, such as a digital video camera or a digital still camera, image blur may be caused by a user's camera shake etc. In order to prevent such image blur, there is a known image pickup apparatus that reduces image blur by driving a plurality of lenses, which are included in a photographing lens unit for forming an image of a subject, in response to a shake amount of the image pickup apparatus caused by camera shake (see Japanese Laid-Open Patent Publication (Kokai) No. 2001-249276 (JP 2001-249276A)). The image pickup apparatus of this publication moves the lenses in directions different from an optical axis direction in order to reduce image blur.
Incidentally, when a lens is moved in a direction different from an optical axis direction, an image distorts and a resolution deteriorates due to eccentric aberration as the shifting amount of the lens from the optical axis increases.
Optical properties of eccentricity aberration are complicated. Particularly, when two or more lenses are moved simultaneously, the optical properties become more complicated, which increases difficulty of the correction. Accordingly, a shake correction system that reduces image blur with two or more movable lenses is desirable to be controlled so as not to move two or more lenses simultaneously from a point of view of correcting eccentric aberration.
However, even if the system is controlled so as not to move two or more lenses simultaneously in order to reduce eccentricity aberration, since an image blur correction effect and an image quality deterioration effect of one lens are different from that of another lens, it is difficult to determine how to move each lens.
Accordingly, a conventional optical device and a conventional image pickup apparatus are difficult to reduce eccentric aberration while reducing image blur.